1. Field of the Invention
The present invention relates generally to filtration apparatus and cartridge filters for use for example in the field of semiconductor production, food industry, pharmaceutical industry and the like and methods of attaching the same, and particularly to filtration apparatus and cartridge filters reliably achieving precision filtration while saving a component associated with the filter and periodically exchanged as the filter""s filtration performance is chronologically impaired and methods of attaching the same.
2. Description of the Background Art
In the fields of electronic component industry, food industry, pharmaceutical industry, pure-water production and the like, filtration apparatus are widely used. For example, electronic components are washed with highly pure agents. If impurity, metal particles or the like in particular, are introduced into these agents, it causes a short circuit or the like between fine interconnections of the semiconductor integrated circuit and the circuit can no longer be expected to normally function. Agents used to wash semiconductor substrates can be repeatedly used and they are thus recycled to safeguard resources, protect environment and also reduce the cost for manufacturing semiconductor devices. However, as has been described above, small metal particles and the like are introduced during the washing and agent recovery process. As such the introduced matters are removed via a filter and then recycled. The filter, initially clean, becomes foul in time as residue attributed to filtering an introduced matter accumulates. The filter in the end would be clogged and no longer sufficiently filter fluid. Accordingly, the filtration apparatus employs a filter periodically exchanged after a set period for use over which the filter""s filtration ability decreases and thus reaches a predetermined level. Thus, a cartridge filter has been used to facilitate exchanging the filter.
FIG. 5 is a view for illustrating a conventional cartridge filter. A housing 110 is configured of a bowl 111, a bag nut 112 and a head 113. Bowl 111 has a step, which engages with a bottom edge of bag nut 112. Head 113 is threaded into bag nut 112 to press an O ring 122 and fix the engagement to integrate bowl 111, bag nut 112 and head 113 together as the housing. Head 113 and bowl 111 have their boundary sealed by O ring 122. Housing 110 has an outlet 115 having an internal opening, which corresponds to a filter receiving portion 125 receiving an attachment 108 of cartridge filter 101. Cartridge filter 101 is configured of an outer cylinder 102, a filter 103 surrounded by the outer cylinder, an inner cylinder (not shown), and top and bottom end caps 106 and 105 fixed to the filter at the top and bottom ends, respectively, fluid-tight. At least one of the two end caps has an opening communicating with the outlet or the inlet. In FIG. 5, top end cap 106 has an opening 107 communicating with outlet 115. Opening 107 also serves as attachment 108 protruding from the end cap outward and inserted into filter receiving portion 125 and attached thereto to allow an O ring 121 fit on the attachment to provide sealing. The attachment attaches through a force provided by a reaction force of O ring 121. In housing 110, head 113 is provided with inlet 114 and outlet 115 arranged to allow fluid to be filtered to be introduced through the inlet, pass through filter 103 and reach the outlet. Head 113 also has a pressure gage connection 116 also serving as an air exhaust port, an air exhaust port 117 and a pressure gage connection 118. Furthermore the bowl has a fluid exhaust port 119. It is needless to say that the air exhaust ports, the fluid exhaust port and the like are closed in operation.
FIG. 6 illustrates a procedure of assembling the FIG. 5 filter apparatus. It can be clearly understood from FIG. 6 that the filter apparatus is configured of integrated filter 101, head 113 and bowl 111. Furthermore, in FIG. 7, attachment 108 with O ring 121 fit thereon is attached to the head""s receiving recess and cartridge filter 101 is thus attached to housing 110.
Using the cartridge filter as described above allows the cartridge filter to be conveniently, periodically exchanged to maintain the filter""s ability of precision filtration having at least a predetermined level.
However, whether exchanging the cartridge filter in the manner as described above is the best way is still an issue to be addressed in order to save resources, minimize refuse, achieve cost reduction, and the like. More specifically, whether exchanging an outer cylinder, a filter, an inner cylinder and top and bottom end caps as one cartridge is the best way or not, is needed to be considered. Desirably, a cartridge should provide a sufficient function of precise filtration while it should have any component thereof saved if possible to contribute to saving resources and minimizing refuse as much as possible.
The present invention contemplates an ecological filtration apparatus and cartridge filter providing a sufficient function of precision filtration while contributing to saving resources and minimizing refuse and a method of attaching the same.
The present invention provides a filtration apparatus including: a housing having an inlet and an outlet; an outer cylinder fixed to the housing; and a cartridge filter configured mainly of a cylindrical filter, an inner cylinder positioned internal to the cylindrical filter and end caps fluid-tight fixed to top and bottom ends, respectively, of the cylindrical filter. The cartridge filter is detachably attached to the housing, accommodated in the outer cylinder, blocking a channel extending from the inlet to the outlet.
Thus, the outer cylinder serves as a housing member and it is not exchanged. This can reduce refuse otherwise corresponding to the outer cylinder and also contribute to saving resources. Furthermore, the material(s) for the outer cylinder can be saved and the cost therefor can thus be saved if the cost for considerations including packing is taken into account. The present filtration apparatus provides a function of precision filtration equal to that of conventional filtration apparatus. Note that the aforementioned cartridge filter corresponds to the ecological cartridge filter of the present invention.
In the above one aspect desirably the filtration apparatus for example has at least one of the end caps that has an opening communicating with the outlet.
Thus, the outer cylinder is positioned close to the inlet receiving a fluid to be filtered and the inner cylinder is positioned close to the outlet outputting the fluid having been filtered. As such in the present invention the inner cylinder, close to the outlet outputting a filtered fluid, is exchanged. This can maintain clean the inner cylinder close to a portion passing a filtered, highly pure agent. The outer cylinder, which is a portion contacting a fluid before it is filtered, is not particularly disadvantageous if it is not exchanged.
Thus, resources can be saved and refuse can be minimized while precision filtration can be achieved to constantly supply a highly pure agent.
In the above one aspect the filtration apparatus can for example be detachably attached and thus fixed to the housing.
As such, if the outer cylinder is for example accidentally damaged the outer cylinder can be independently exchanged. Furthermore, if between the outer cylinder and the filter the outer cylinder""s inner surface is for example severely contaminated the outer cylinder can be removed and cleaned with an agent. Thus, precision filtration can be constantly provided to supply a highly pure agent.
The present invention provides a cartridge filter detachably attached to a housing, arranged internal to an outer cylinder fixed to the housing. The cartridge filter includes: a cylindrical filter; an inner cylinder positioned internal to the cylindrical filter; and end caps fluid-tight fixed to top and bottom ends, respectively, of the cylindrical filter.
The ecological cartridge filter configured as above can eliminate the necessity of exchanging the outer cylinder that essentially does not have a significant effect on the filter""s performance. This can in turn eliminate the necessity of producing and selling a component other than the ecological cartridge filter, a portion essentially requiring exchanging, to save resources and reduce refuse.
The present invention provides a method of attaching a cartridge filter, including the steps of: with a filtration apparatus having a housing released, inserting into an outer cylinder fixed to the housing a cartridge filter formed mainly of a cylindrical filter, an inner cylinder and top and bottom end caps, to attach the cartridge filter to the housing; and sealing the housing having the cartridge filter attached thereto, to form a channel extending from an inlet to an outlet.
Thus, the outer cylinder can almost be free from exchange or it can be exchanged less frequently than the filter. This can save resources corresponding to the outer cylinder and reduce refuse otherwise corresponding to the outer cylinder.
The foregoing and other objects, features, aspects and advantages of the present invention will become more apparent from the following detailed description of the present invention when taken in conjunction with the accompanying drawings.